Production of pergamyn



United States Patent 3,021,253 PRGDUCTION OF PERGAMYN Fritz Opderbeck, Frankfurt am Main-Okriftel, and Gunther Trapp and Gunther Worner, Okriftel (Main), Germany, assignors to Phrix-Werke A.G., Hamburg, German Nolbrawing. Filed Feb. 3, 1953, Ser. No. 713,046 Claims priority, application Germany Feb. 2, 1957 9 Claims. (Cl. 16213) The present invention relates to an improvement in the production of pergamyn which is an artificial parch ment paper, and more particularly to an improvement during the beating of pulp which improves the resulting product and more rapidly makes it available for working up into final cellulose products such as pergamyn.

Pergamyn is used at the present time for the packaging of foodstuffs, as tracing paper, and for other purposes. To a great extent pergarnyn has replaced natural parchment. It is necessary in the production of pergamyn to beat the cellulose pulp until the cellulose attains a smeary consistency. This type of beating generally requires a long period of time and consequently a great deal of energy. Particularly long beating periods in a hollander beater are necessary in order to make pulp suitable for the production of pergamyn because parchment papers of satisfactory transparency and a sufficient degree of resistance to grease can be produced only with pulp having a high grade of freeness.

This parchment property is generally ascertained by means of the so-called bubble test. This property is an important criterion for the behavior of crude pergamyn during calendering. The bubble test consists of applying the paper to a hot surface. Before the paper gets brown larger or smaller bubbles are produced because the vapor produced within the paper cannot escape immediately due to the toughness and coherence of the paper. The larger these coherent bubbles, the better the quality of the paper. The bubble test may be carried out manually by holding a burning match under the paper to be tested. 1 It is a primary object of the present invention to provide for a means of improving the beating of cellulose pulp particularly to an extent of reducing the beating time necessary to give to the pulp a sufficiently high degree of freeness to make the same suitable for the production of pergamyn.

It is another object of the present invention to provide for a new method of treating cellulose pulp whereby beating of the pulp to increase the freeness thereof is.

facilitated and in addition the properties of the finally A obtained beaten pulp are improved.

Other objects and advantages of the present invention will be apparent from a further reading of the specification and of the appended claims.

With the above objects in view, the present invention mainly consists in a method of producing cellulose products according to which method the cellulose pulp is beaten in the presence of a cellulose-digesting enzyme. Cellulose pulp beaten in this manner, that is in the presence of a cellulose-digesting enzyme, is particularly suitable for the production of pergamyn.

It has been established in accordance with the present invention that the beating period of pulp can be considerably reduced if the pulp is beaten in the presence of a cellulose-digesting enzyme. For this purpose various types of cellases which are formed by various different microorganisms may be used.

The cellase-containing preparations can be obtained from fungi which are forced by repeated cultivation in the presence of cellulose to produce large amounts of cellase.

3,2l,253 Patented Feb. l3, 3%62 In the application of the process of the present invention on an industrial scale a stock of Aspergillus oryzae may be utilized which has been cultivated on wheat bran by the addition of cellulose based on the principles of surface cultivation. Instead of Aspergillus oryz ze it is equally suitable to utilize Aspergillus niger.

After the myceliurn has been formed it is destroyed by grinding in the presence of water in order to expose the enzyme and the celiase which is dissolved in the water is separated from the culture medium by filtration.

Other raw materials may also be used for the production of suitable cellase-containing enzyme preparations.

The cultivation of the organism may be carried out by means of surface cultivation or submersed cultivation. Under certain conditions other bacteria such as Myr thecium verrucaria, Lenzites saepiaria, thermo-bacteria and protozoa can be used for producing the cellase. It is also possible to obtain the cellase from natural sources such as from vineyard snails.

In accordance with the present invention the temperature utilized during the beating process may be the same as that usually utilized in the known beating methods, that is about room temperature. When carrying out the beating in accordance with the method of the present invention slight temperature increases due to frictional heat may actually be of some advantage. However, it is preferred to prevent any increase of temperature above 25 C. in order to avoid any detrimental action on the cellulose.

It is further preferred in accordance with the present invention to maintain the pH value of the material in the hollander beater at approximately the neutral pH range. It is possible that during prolonged beating procedures the pH value of the material being beaten may be slightly shifted into the acid region due to enzymatic processes. In order to prevent this the solution may be buffered to a pH value of approximately 7 by the addition of suitable substances such as disodium'phosphate in the presence of citric acid.

The enzyme concentration in the material to be beaten may, in accordance with the present invention, vary within extremely wide limits. For example, during the experiments carried out for the purposes of this invention 100 grams of the culture medium dry substance were dispersedin 1 liter of tap water. 350 cc, of the filtered extract were used per 100 grams of pulp. Experiments have shown that the accelerating effect on the grinding process does not substantially decrease even if the enzyme solution is diluted to /2 the concentration or even to A the concentration. The optimum ratio of culture medium to pulp has been found to be 1:1, the maximum ratio to be 2:1 and the minimum ratio 10 grams of culture medium to 100 grams of pulp, i.e. 0.111. a a

The basic advantage of the present invention as shown by experiments which were carried out is that the degree of freeness, which is measured according to the Schopper- Riegler system, increases much more rapidly no matter what type of pulp is beaten in a hollander beater if a cellulose-digesting enzyme is present during the beating. Thus, as compared to the usual types of beating in pure water, the beating in accordance with the present invention which is carried out in the presence of a cellulosedigesting enzyme is greatly accelerated.

The shortening of the beating period amounts to 20 25% depending upon the type of cellulose utilized. In addition, and this is a rather remarkable effect, if the heating is carried out in the presence of a celluloseing to Schopper-Riegler is necessary in order for the pulp to be suitable for the production of pergamyn. However, if the beating is carried out in the presence of a cellulose-digesting enzyme in accordance with the present invention the pulp may be suitable for the production of pergamyn at a lower freeness value, i.e. at approximately 67-70. This lowering of the required freeness value for the parchmenting threshold results in a further shortening of the beating period, which of course results in substantial saving of power.

The tensile strength of the finally obtained paper product increases much faster when the beating is carried out 1n the presence of a cellulose-digesting enzyme in accordance with the present invention than when the heating is carried out in pure water, although the same maximum values may be attained in either case. (The so-called Rieth hollander is generallyused.) This phenomenon, the fact that the maximum strength of the paper is more quickly achieved byproceeding in accordance with the method of the present invention, may be due to the microscopic structure of the material resulting from the treatment of the present invention. Microscopic examination has shown that fibers beaten in the presence of a cellulose-digesting enzyme show more longitudinal fibrillation and has more fuzz at the ends than is the case of fibers beaten in the normal manner.

The results which are obtained by proceeding in accordance with the present invention are particularly marked in the case of the beating of pinewood pulp which is obtained by digesting according to the sulfite process. This speeding up due to the beating being carried out in the presence of the cellulose-digesting enzyme may also be observed when beating sulfate pulp, although the advantage is less pronounced in such case due to the fact that relatively prolonged beating periods are in any event required for pulp of this type. Bufiering of the hollander content to a value of approximately pH 7 seems to be particularly advantageous in the case of sulfate pulp since it results in a much more rapid increase of the freeness value and in firmer sheets.

Large-scale tests have shown that when beating a pinewood sulfite pulp together with a cellulose-digesting enzyme in a stone hollander in accordance with the method of the present invention better parchmentation is achieved in a period of 1 /z2 hours than can be achieved in the case of normal beating in the presence of only pure water carried out over a period of 2 /2 hours. Freeness grade measurements resulted in a Schopper-Riegler grade of 81 in the case of grinding only 2 hours in the presence of enzymes as compared to a grade of only 75 in the case of grinding 2 /2 hours without the enzymes being present.

The pulp which is beaten in accordance with the present invention is driven out over the paper machine, subsequently moistened and calendered in the usual manner without any difficulty. The air permeability and the surface smoothness of the pergarnyn which is obtained by the beating in the presence of the enzyme in accordance with the present invention isclearly superior to the same properties of pergamyn obtained from pulp which is beaten in the normal manner. The tensile strength values were at least as high, and generally somewhat higher, than those obtained from pulp beaten in the presence of water alone.

The following examples are given to further illustrate the present invention. The scope of the invention is not, however, meant to be limited to the specific details of the examples.

Example 1 A pinewood pulp digested by the sulfite process in the usual manner is soaked in an extract obtained from an Aspergillus oryzae preparation which was cultivated on wheat bran and has a diastatic power of 80. of the culture were used per 100 grams of pulp. The soaked substance is then beaten in a so-called Rieth hollander at a density of 4. For comparison purposes the 100 grams 7 .and a moisture content of about 60%.

same substance is also processed in the same manner in pure water under identical conditions.

The material beaten in the presence of the enzyme extract has a freeness grade according to Schopper-Riegler of 70 after only minutes and yields an excellent pergamyn'of standard strength. As compared thereto, the material beaten with water has a freeness grade of only 65-66 after 80 minutes, and cannot be used for the production of pergamyn paper. Only after continuing beating for a total time of minutes is it possible to obtain a pergamyn of approximately similar properties. The freeness value of the pulp beaten in pure Water after 110 minutes according to Schopper-Riegler is 76-77.

The product obtained by multiplying the freeness grade by the grinding time, which may be considered the parchmenting threshold, is 8470 in the case of the pulp beaten in water in the usual manner, and is only 5600 in the case of pulp beaten in the presence of the cellulose-digesting enzyme in accordance with the present invention. These figures show in a pronounced manner the considerable saving in beating energy which is achieved by proceeding in accordance with the method of the present invention. Not only is the beating itself accelerated by the presence of the enzyme, but the beaten pulp is suitable for parchmenting at a lower freeness grade.

Example 2 A culture of Aspergillus oryzae is cultivated on 350 kg. of wheat bran, the mycelium disintegrated and the extract filtered from the bran. 6.5 cubic meters of extract are obtained, which have a diastatic power of 100. 216 kg. of moistened pinewood pulp digested by the sulfite process and 105 kg. of edge-mill product are soaked in this 6.5 cubic meters and beaten for two hours after a short disintegration. The pinewood pulp has a permanganate number of 90 to 100, a whiteness of approximately 82 (The edge-mill product is the refuse paper which used to be added to the hollander mixture upon treatment in the edge-mill grinder.) The temperature during the grinding process does not exceed 25 C. although no special measures are taken.

For comparison purposes 300 kg. of the same material are ground in the same hollander under only water. Both batches are independently processed on the same paper machine into crude pergamyn, moistened as usual, stored for 24 hours and finally calendered. The results maybe seenin the following table:

Freeness Break- Elonga- Bursting Number Grinding, hours grade, ing tlon, pressure, of

8.13.. length, percent lrgjcrn. foldlngs 1% hrs. with enzyme 72 8, 410 3. 39 3. 28 1, 545 2 hrs. with enzyme 81 8, 485 3. 36 3. 36 996 2% hrs. with only water (no enzyme)- 75 8, 3. 40 3. 29 1, 091

It is evident that the same substance when ground in the presence of the enzyme solution yields after only one and a half hours a freeness grade of 72 Schopper-Riegler, while when ground with water it took two and a half hours to attain a freeness of 75 S.R. The tensile strength of the paper processed with enzymes was found to be considerablyhigher even after one and a half hours of grinding than in the case of the water-processed product ground for two and a half hours.

The bubble test of the pergamyn produced from a pulp ground for two hours with enzymes was far more positive than the one carried out on a two-and-a-half hour, waterprocessed material. Both the air permeability and the smoothness of the pergamyn manufactured in accordance with theprocedure suggested inthis invention are much better than are these characteristics of the standard, waterprocessed pergamyn. The grease-proof properties were identical for the two kinds of paper products.

The above information shows that the invention not only brings forth a considerable saving in grinding effort and consequently a substantial increase of hollander capacity but also that the characteristics of the final product are improved.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can be applying current knowledge readily adapt it for various applications Without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a method of producing cellulose products, the step of beating a digested cellulose pulp in the presence of a cellulose-digesting enzyme.

2. In a method of producing pergamyn, the steps of digesting Wood pulp; beating the thus-formed digested cellulose pulp in the presence of a cellulose-digesting enzyme; and converting the thus-beaten pulp to pergamyn.

3. In a method of producing pergamyn, the steps of beating in a heater a cellulose pulp at an approximately neutral pH in the presence of a cellulose-digesting enzyme; and converting the thus-beaten pulp to pergamyn.

4. In a method of producing cellulose products, the step of digesting wood pulp; beating the thus-formed digested cellulose pulp in a heater at an approximately neutral pH in the presence of a cellulose-digesting enzyme at a maximum temperature of 25 C.

5. In a method of producing pergamyn, the steps of beating in a heater a cellulose pulp at an approximately neutral pH in the presence of a cellulose-digesting enzyme at a maximum temperature of 25 C.; and converting the thus-beaten pulp to pergamyn.

6. In a method of producing cellulose products, the step of beating in a heater a cellulose pulp in the presence of a cellulose-digesting enzyme obtained by the cultivation of an organism selected from the group consisting of Aspergil'lus olyzae and Aspergillus niger.

7. In a method of producing pergamyn, the steps of beating in a heater a cellulose pulp in the presence of a cellulose-digesting enzyme obtained by the cultivation of an organism selected from the group consisting of Aspergillus oryzae and Aspergillus niger; and converting the thus-beaten pulp to pergamyn.

8. In a method of producing pergamyn, the steps 01 beating in a heater a cellulose pulp at an approximately neutral pH in the presence of a cellulose-digesting enzyme obtained by the cultivation of an organism selected from the group consisting of Aspergillus oryzae and Aspergillus niger; and converting the thus-beaten pulp to pergamyn.

9. In a method of producing pergamyn, the steps of beating in a heater a cellulose pulp at an approximately neutral pH in the presence of a cellulose-digesting enzyme obtained by the cultivation of an organism selected from the group consisting of Aspergillus oryzae and Aspergillus niger at a maximum temperature of 25 C.; and converting the thus-beaten pulp to pergamyn.

References Cited in the file of this patent UNITED STATES PATENTS 2,280,307 Diehm Apr. 21, 1942 2,839,398 Stuck June 17, 1958 FOREIGN PATENTS 287,884 Germany Oct. 8, 1915 OTHER REFERENCES Waksman et al.: Enzymes, Williams and Wilkins Co., Baltimore, Md. (1926), pp. 149-150. 

2. IN A METHOD OF PRODUCING PERGAMYN, THE STEPS OF DIGESTING WOOD PULP; BEATING THE THUS-FORMED DIGESTED CELLULOSE PULP IN THE PRESENCE OF A CELLULOSE-DIGESTING ENZYME; AND CONVERTING THE THUS-BEATEN PULP TO PERGAMYN. 